In Moses 6: 59-60 there is a pattern that intrigues me. It speaks of being born by water, blood, and the spirit and those words are used three times.
The first time it says that we are “born into the world by water, and blood, and the spirit which I have made.” This all happens during the process of childbirth.
Then it tells us we must be “born again into the kingdom of heaven, of water, and of the Spirit, and be cleansed by blood, even the blood of mine Only Begotten.”
I really like the analogy of being “born again.” When we are baptized and have our sins washed away, it is as if we are a new born babe, fresh from the heavens and without sin. We can become again this way each Sabbath as we renew our baptismal covenants by partaking of the sacrament.
Then it tells us why we must be born again by these three things and what part they play.
“For by the water ye keep the commandment; by the Spirit ye are justified, and by the blood ye are sanctified.”
We are baptized in water and by so doing keep the commandment. It is up to the Holy Ghost to justify the ordinance. In the class The Eternal Family we studied this and learned about what the justification of the Spirit means.
“We are “justified” by the Spirit as the Holy Spirit of Promise either ratifies or rejects each ordinance as being valid.”
“[Justification] is the Lord’s way of assuring that no unauthorized acts or ordinances are binding in the hereafter.” 
These are pretty amazing responsibilities that the Holy Ghost has. This also reminds us that we can’t fool the Lord. If we enter covenants unworthily, they may look like they have been done, but the Spirit will not justify the ordinance as being valid.
And then after those two things have happened, we are able to be sanctified by the blood shed for us by our Savior Jesus Christ. The dictionary defines sanctified as to "set apart as or declare holy; consecrate; make legitimate or binding by religious sanctification; free from sin; purif[ed]."
 Justification and Sanctification Transcript, The Eternal Family, BYU-Idaho, taken partially from Elder D. Todd Christofferson, Born of God, April 2008
 Elder Bruce R. McConkie, Mormon Doctrine, p. 408